1. Field of the Invention
The present invention relates to armature winding structures of dynamo-electric machines. In particular, the present invention relates to a stator winding structure of an alternator, for example, an automotive alternator to be mounted on an automotive vehicle, such as an automobile or a truck.
The entire content of the basic Japanese Patent Application from which the priority under the Convention is claimed in this application is hereby incorporated by reference into this application.
2. Description of the Related Art
In recent years, reduced sizes, increased outputs, and improved quality have been increasingly required of alternators. In order to obtain an increased output from an alternator reduced in size, it is important to distribute magnetic loading and electrical loading in a most appropriate manner and at a highest possible concentration within a limited volume.
The outputs of automotive alternators must be increased because of increasing vehicle loads while engine compartments become smaller, thereby reducing spaces for mounting the alternators. Also, there are requirements to reduce the noise of the automotive alternators which operate all the time for supplying electricity, the noise becoming relatively large with respect to the engine noise which has been reduced in response to the requirements to reduce the noise generated toward the outside and the inside of the vehicle compartments. The automotive alternators, which operate all the time, are required to have a very high heat resistance because of their severe operating thermal condition in which the alternators are heated by high Joule heat generated by the output current.
In order to reduce the size and increase the output of an alternator, the resistance of a stator winding must be reduced, the space factor of electrical conductors in magnetic circuits of the stator must be increased, and the bridge portions (bridge portions outside a stator core are called coil ends) of the stator winding must be set in order and be concentrated. Furthermore, the requirements for heat resistance, reduced noise, and the like must be complied with.
A structure for reducing the resistance of windings (heat loss), improving the space factor of electrical conductors, and lining up and concentration of coil ends was proposed disclosed in, for example, International Publication No. WO92/06527, in which short conductor segments having large cross-sections are used as electrical conductors of the stator winding.
In an alternator of this type, the reduction of turns of the stator winding for each phase is effective for reducing the armature raction which causes decrease in the output in a high-rotation range of, for example, 2000 to 5000 rpm. Particularly, the turns can be reduced by reducing the number of electrical conductors received in a slot, by which the flatness ratio (the size of the sections of the conductors in the slot-depth direction divided by the size of the same in the slot-width direction) of the electrical conductors increases. However, since short conductor segments formed in a U-shape by bending conductors having a rectangular section are used as the electrical conductors, it is difficult to form turn portions of the conductor segments as the flatness ratio of the electrical conductors increases. Therefore, it is necessary for reducing the turns for each phase of the stator winding to increase the number of the electrical conductors received in a slot so as to reduce the flatness ratio of the electrical conductors, thereby making the formation of the turn portions easy, and to connect in parallel the windings formed by connecting the electrical conductors.
A technology is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2000-92766, in which lap windings (loop windings) and wave windings each constructed by joining short conductor segments are connected in parallel to each other, thereby forming winding phase group for each phase of the stator winding.
As shown in FIG. 19, the known stator winding include three types of conductor segments 311, 312, and 313 made of a conductor having a rectangular section and formed substantially in a U-shape. Each of the conductor segments 311, 312, and 313 is inserted at the ends thereof in a pair of slots three slots apart (at a magnetic pole pitch) from an end of each slot in the axial direction, and the ends of the conductor segments 311, 312, and 313 extending from the other end of the same slots are connected to each other by welding or the like, thereby forming a coil of windings in four turns around the stator core. In each slot, six conductors are disposed alongside each other in a radial direction of the stator core, the six conductors being two sets of in-slot-received portions 311a, 312a, and 313a of the conductor segments 311, 312, and 313, respectively. The positions in each slot which are occupied by the six in-slot-received portions 311a, 312a, and 313a are hereinafter referred to as first address, second address, . . . , sixth address from the innermost toward outer positions in a radial direction of the stator core. A turn portion 313b of the conductor segment 313 is covered by a turn portion 312b of the conductor segment 312, and the turn portion 312b of the conductor segment 312 is covered by a turn portion 311b of the conductor segment 311, at an axial end face of the stator core.
At an axial end opposite to the axial end of the stator core at which the turn portions 311b, 312b, and 313b protrude, an end 313c of the conductor segment 313 extending from the third address of a slot is connected to an end 313c of the other conductor segment 313 extending from the fourth address of another slot three slots apart, thereby forming two winding sub-portions 301 and 303 each constructed with a wave winding, each in one turn per slot. An end 311c of the conductor segment 311 extending from the first address of a slot is connected to an end 312c of the conductor segment 312 extending from the second address of another slot three slots apart, and the end 312c of the conductor segment 312 extending from the fifth address of a slot is connected to the end 311c of the conductor segment 311 extending from the sixth address of another slot three slots apart, thereby forming two winding sub-portions 302 and 304 each constructed with a lap winding, each in two turns per slot.
As shown in FIG. 20, each of winding phase groups for three phases, each in six turns, is formed by connecting in series the two winding sub-portions 301 and 303, and the two winding sub-portions 302 and 304. In FIG. 21, each of winding phase groups for each turn, each in three turns, is formed by connecting in series the winding sub-portion 301 and the winding sub-portion 302, and the winding sub-portion 303 and the winding sub-portion 304, and connecting in parallel the series-connected winding sub-portions 301 and 302 and the series-connected winding sub-portions 303 and 304. Three sets of the winding phase groups thus formed are connected into an alternating connection, thereby forming a three-phase alternating winding constituting a stator winding, the stator winding being connected to a rectifier.
The known stator winding of an automotive alternator are formed in a manner such that three types of the conductor segments 311, 312, and 313 are inserted in a pair of slot separated by a distance of one magnetic-pole pitch from an end of the stator core so that the in-slot-received portions 311a, 312a, and 313a overlap each other, and the ends of the conductor segments 311, 312, and 313 extending from the other end of the stator core are connected to each other.
In the known stator winding formed as described above, the height of the coil ends of the stator winding at the end of the stator core 15 is increased, as shown in FIG. 22, whereby a problem has been found in that the alternator including the stator winding cannot be reduced in size, and due to an increased resistance of the stator winding, heat loss becomes large, the heat generation increases at the stator winding, and the leakage reactance at the coil ends increases, whereby the output cannot be increased.
Since the turn portion 313b is covered by the turn portion 312b and the turn portion 312b is covered by the turn portion 311b, the exposure area of the coil ends of the stator winding at the end of the stator core 15 is reduced, whereby the stator winding is not efficiently cooled. Therefore, the stator winding is heated up and the output cannot be increased.
One set of three-phase alternating winding is mounted on the stator core having one slot per phase per pole, and the output thereof is rectified by one rectifier. That is, a small number of the turn portions extending from the slots are disposed in the circumferential direction, whereby the cooling cannot be performed efficiently. Therefore, the stator winding are heated up and the output cannot be increased. The heat loss per one rectifying diode increases because only one rectifier is provided, the temperature rises, and an increased output is difficult to obtain.
Accordingly, it is an object of the present invention to provide a high-output dynamo-electric machine reduced in size and easy to manufacture, in which n-pairs of first wave windings and second wave windings are provided, the first wave windings being formed with a first winding wound in a wave-shape in one turn per slot and the second wave windings being formed with a second winding wound in a wave-shape in one turn per slot, the second winding being offset from the first winding by an electrical angle of 180 xc2x0 degrees so as to be opposite to the first winding, and two sets of series-connected windings in n-turns are connected in parallel, each set of the series-connected windings including the first and second windings for each phase, which respectively include n-wires, connected in series.
It is another object of the present invention to provide a high-output electrical rotating apparatus which includes two slots per pole per phase and a stator winding including two sets of alternating winding, each set being formed with the stator winding for each phase connected in an alternating connection so as to be rectified by one rectifier, whereby coil-end portions of the stator winding can be effectively cooled and the loss in rectifier diodes is reduced.
According to an aspect of the present invention, a dynamo-electric machine comprises:
an armature including an armature core provided with a plurality of slots extending in an axial direction of the armature core and disposed alongside each other in a circumferential direction of the armature core, and an armature winding mounted in the slots provided on the armature core,
wherein the armature winding comprises first wave-shaped windings and second wave-shaped windings, the first wave-shaped windings comprising a number of first winding sub-portions each having one turn constructed by winding in a wave-shape a strand of wire so as to alternating occupy an inner layer and an outer layer in a slot-depth direction within the slots at intervals of a predetermined number of slots, the first winding sub-portions being disposed at a pitch of one slot from each other and being equal in number to the predetermined number of slots, and the second wave-shaped windings comprising a number of second winding sub-portions each having one turn constructed by winding in a wave-shape a strand of wire so as to alternating occupy an inner layer and an outer layer in a slot-depth direction within the slots at intervals of the predetermined number of slots and so as to be inversely wound and offset by an electrical angle of 180 degree relative to the first winding sub-portions, the second winding sub-portions being disposed at a pitch of one slot from each other and being equal in number to the predetermined number of slots, whereby n-pairs (n represents a natural number) of the first wave-shaped windings and the second wave-shaped windings are disposed so as to arrange alternately and in a row in-slot-received portions of the first winding sub-portions and in-slot-received portions of the second winding sub-portions in the slot-depth direction within each of the slots; and
wherein the armature winding includes winding phase groups for each phase, each of the winding phase groups comprising 2n windings composed of the first and second winding sub-portions disposed in a group of slots at intervals of the predetermined number of the slots, two sets of the n windings being connected in series to form two series-connected windings each having n-turns, whereby the winding phase group is constructed by connecting the two series-connected windings in parallel.
The two series-connected windings may comprise first series-connected winding having n-turns formed by connecting in series the first winding sub-portions disposed in the group of slots and second series-connected winding having n-turns formed by connecting in series the second winding sub-portions disposed in the same group of slots as the group of the slots in which the first winding sub-portions are disposed.
An expression n=2m+1 (m represents a natural number) may be satisfied.
The strand of wire may be a substantially U-shaped conductor segment, and each of the first winding sub-portion and the second winding sub-portion may include a plurality of the conductor segments forming a wave winding in one turn connected to each other at the open ends thereof.
The strand of wire may be a continuous conductive wire, and each of the first winding sub-portion and the second winding sub-portion may include a single continuous conductive wire forming a wave winding in one turn.
Each pair of the first wave-shaped windings and the second wave-shaped windings may be formed with individual wire assemblies including a plurality of the first winding sub-portions and a plurality of the second winding sub-portions.
The strand of wire may be a conductor having a substantially circular cross-section.
The two series-connected windings for each phase forming the armature winding may be connected to each other via a metallic terminal.
The armature core may be a cylindrical stator core made of a laminated iron core, further the dynamo-electric machine may comprise a rotor forming N and S poles along the rotational periphery thereof, the rotor being disposed at an inside of and coaxially with the stator core, and a fan unit fixed to the rotor at the axial ends thereof for applying cooling air to coil-end groups of the armature winding by the rotation of the fan unit.
The n-pairs of the first wave-shaped windings and the second wave-shaped windings may include protrusions thereof from the axial ends of the stator core decreasing gradually toward the outside in the radial directions of the stator core.
According to another aspect of the present invention, a dynamo-electric machine comprises:
an armature including an armature core provided with a plurality of slots extending in an axial direction of the armature core and disposed alongside each other in a circumferential direction of the armature core, and armature winding mounted in the slots provided on the armature core,
wherein two slots per pole per phase are formed in the armature core;
wherein the armature winding comprises two alternating windings, each formed by connecting winding phase groups for each phase into a alternating connection;
wherein each of the winding phase groups for each phases is formed by connecting in parallel two windings each having n-turns (n represents a natural number), the windings being constructed by winding a strand of wire in the armature core so as to dispose 2n in-slot-received portions of the strand of wire within each of the slots alongside each other in the slot-depth direction and so as to connect each in-slot-received portion in a first slots to other in-slot-received portions occupying addresses, in the slots individually separated from the first slot by a predetermined number of slots, differing in the slot-depth direction from that which is occupied by the in-slot-received portion in the first slot, at the outside of the slots; and
wherein the individual alternating current outputs from the two alternating windings are rectified by first and second rectifiers, respectively, and outputted by being combined with each other.
N-rows of coil ends, each coil end being formed by connecting the in-slot-received portion in the first slots to the other in-slot-received portion occupying addresses, in the slots individually separated from the first slot by the predetermined number of slots, differing in the slot-depth direction from that which is occupied by the in-slot-received portion in the first slot, may be formed at at least one of the axial ends of the armature core, and the protrusion, in the axial direction, of the n-rows of the coil ends may be decreases gradually toward the outside in the radial direction of the armature core.
N-rows of coil ends, each coil end being formed by connecting the in-slot-received portion in the first slots to the other in-slot-received portion occupying addresses, in the slots individually separated from the first slot by the predetermined number of slots, differing in the slot-depth direction from that which is occupied by the in-slot-received portion in the first slot, may be formed at at least one of the axial ends of the armature core, and the coil ends in the n-rows may be arranged substantially evenly in the circumferential direction of the armature core.
Coil ends, each being formed by connecting the in-slot-received portion in the first slots to the other in-slot-received portion occupying addresses, in the slots individually separated from the first slot by the predetermined number of slots, differing in the slot-depth direction from that which is occupied by the in-slot-received portion in the first slot, may be stacked up in n-layers in the axial direction of the armature core at at least one of the axial ends of the armature core, and the coil ends in the n-layers may be arranged substantially evenly in the circumferential direction of the armature core.
Each strand of wire may be formed with substantially U-shaped conductor segments.
Each strand of wire may be formed with a continuous conductive wire.
An insulating resin may be disposed at at least one of the axial ends of the armature core and between the two windings each having n-turns forming the winding phase groups for each phase.